Stable insecticidal preparations in the form of aqueous emulsion or suspension

ABSTRACT

Physically and chemically stable insecticidal preparation in the form of aqueous emulsion or suspension is provided wherein active ingredients which are oily or solid and hardly soluble or insoluble in water are mixed in water with nonionic surfactants having an HLB value of 11 or less and thickeners.

This is a continuation-in-part of Patent Application Ser. No. 904,765 filed Sep. 5, 1986 which is a continuation of Ser. No. 727,556 filed Apr. 26, 1985 which is a continuation-in-part of Ser. Nos. 655,374 and 655,375 filed Sep. 27, 1984 and Sep. 27, 1984, respectively, which are continuation-in-part of Ser. Nos. 615,456 and 615,321 filed May 30, 1985 and May 30, 1985, respectively. All are now abandoned.

The present invention relates to an improvement in an agricultural chemical preparation in the form of aqueous emulsion or suspension, said preparation containing insecticides, herbicides or fungicides.

So far as insecticidal preparations in particular, for instance, are concerned, they are usually in the form of emulsifiable concentrates, wettable powders, dusts, flowables and the like. Desired forms are chosen depending on the purposes. An aqueous preparation is preferred, because it is able to be formulated using water in place of organic solvents which often cause toxicity problems like phytotoxicity or irritation and safety problems in production, storage, transportation or application thereof.

Active ingredients used in insecticidal preparations in the form of aqueous emulsion or suspension heretofore proposed are usually hydrophobic or solid at room temperature. Any of oil-in-water emulsion formulation containing a liquid active ingredient at room temperature has not yet been put on the market, because shelf life is not long, i.e., short in stability in water. The word "stability" herein means "physical stability", i.e., separation to phases and "chemical stability", i.e., decomposition of active ingredients.

There are oil-in-water type emulsion formulations. Some of them are suspension in water containing thickeners without surfactants, or emulsion in water containing surfactants without thickeners. The former suspension is hard to keep emulsion for a long time, while the latter emulsion accompanies hydrolysis of active ingredients by surfactants during the storage until the ingredients are decomposed and they no longer work as insecticides, although there is little separation into different phases. Problems in the presence of surfactants left unsolved are short shelf life due to decomposition of active ingredient(s) and unavoidable strong irritations to eyes, nose and throat. Therefore, the active ingredients employed in such formulations must be limited to those which have high stability even when emulsified or dispersed in water by the aid of a surfactant or thickeners.

U.S. Pat. No. 4,306,640 (Fuyama et.al.) discloses that general-purpose synthetic surfactants have drawbacks in stability of the active ingredient and that oil-in-water insecticidal emulsion in issue does not employ any general purpose synthetic surfactants, but polyvinyl alcohol or gum arabic as a most suitable dispersing agent. However, polyvinyl alcohol is not surfactants ("The Merck Index, page 986, No. 7363 (1976)) and gum arabic is not general purpose synthetic surfactants but emulsifying agents only for food (Martin Glicksman, "Gum Technology in the Food Industry", p. 104 (1969)), Canadian Patent No. 1145252 discloses that nonionic surfactants except that having an aromatic ring substituted with at least one aryl radical or aralkyl radical fail to give stable emulsion. The patent does not refer to chemical stability of active ingredients, but physical stability of emulsion. U.S. Pat. No. 4,173,651 discloses an insecticidal composition in which water or aliphatic hydrocarbons having a boiling point of 150°-350° C. are used as solvents, but the patent refers to neither physical stability nor chemical stability in the case of emulsion. U.S. Pat. No. 4,399,287 discloses pesticidal and in particular herbicidal compositions in which water with a surface active agent are used, but is silent on stability.

Surfactants having HLB of-12 or more have been used in aqueous compositions of water insoluble insecticides, in order to stabilize emulsion. U.S. Pat. No. 3,948,636 discloses a flowable aqueous preparation of waterinsoluble insecticide in which surfactants employed are the ethoxylated alkylphenols, i.e., alkylaryl polyether alcohols of the general formula ##STR1## wherein R=a C₈ -C₁₂ alkyl group and y=an integer of 8-30. Within this class, a compound having a C₈ -alkyl group and y=an integer of 8 has the lowest HLB of 12.06. Others are as follows.

R=C₉, y=9 HLB 13.36

R=C₉, y=15 HLB 15.26

R=C₁₀, y=9 HLB 13.08

R=C₁₀, y=15 HLB 15.03

After the present inventors' extensive study to find a method for producing an agricultural chemical preparation of either aqueous emulsion or suspension in a simple manner, they succeeded to find the fact that any of solid or oily active ingredients which are hardly soluble or insoluble in water but soluble in or miscible with surfactants at room or elevated temperature are able to be formulated into a storage-stable aqueous preparation. In accordance therewith, insecticidal chemical preparations are obtained in which the suspensions physically stable and the active ingredient are held chemically stable for a long period of time. Furthermore the preparations are handled without any risk of inflammation in the storage or transportation thereof and markedly decreased in the toxicity to mammals.

Accordingly to the present invention, the use of nonionic surfactants having HLB value of 11 or less, preferably having HLB value of 10 or less, gives chemical stability of the ingredients as well as physical stability of the preparations for a long time of period such as two or three years. Addition of thickeners makes viscosity of the preparation suitable for spraying.

The present insecticidal preparation in the form of aqueous emulsion or suspension comprises

(1) 0.5 to 60% by weight of one or more active ingredient(s),

(2) 0.3 to 50% by weight of one or more nonionic surfactant(s) having an HLB value of 11 or less,

(3) a thickener, and

(4) the balance of water.

The active ingredient is hardly soluble or insoluble in water (i.e., the solubility in water being 1% by weight or less at 20° C.). The oily ingredient means to include oily and semioily ones and is soluble in or miscible with the nonionic surfactant at room or elevated temperatures (i.e., about 20° to 50° C.). The solid ingredient is still insoluble in the nonionic surfactant even at elevated temperature. It is preferred that an amount of the solid ingredient is small when oily ingredients with solid ones are employed.

In case of a solid or powder technical material is employed, it is desirable to make it fine particles by any conventional milling equipment before mixing to prepare the suspension. The order of adding the ingredients is critical especially when a liquid technical material is employed.

Insecticides

They may be any of organophosphates, pyrethroides, carbamates or others.

(1) Organophosphate insecticides

Cyanophos [0-(4-cyanophenyl) 0,0-dimethyl phosphorothioate]

Diazinon [0,0-diethyl 0-2-isopropyl-6-methylpyrimidin4-yl phosphorothioate

Dichlorvos [2,2-dichlorovinyl dimethylphosphate]

Prothiophos [0-2,4-dichlorophenyl 0-ethyl-S-propyl phosphorodithioate]

Chloropyrifos [0-3,5,6-trichloro-2-pyridyl 0,0-diethyl phosphorothioate]

Fenitrothion [0,0-dimethyl 0-4-nitro-m-tolyl phosphorothioate]

Fenchlorphos [0,0-dimethyl 0-2,4,5-trichlorophenyl phosphorothioate]

Fenthion [0,0-dimethyl 0-4-methylthio-m-tolyl phosphorothioate]

Bromophos [0-4-bromo-2,5-dichlorophenyl 0,0-dimethyl phosphorothioate]

Malathion [S-1,2-bis(ethoxycarbonyl)ethyl 0,0-dimethyl phosphorodithioate]

Chlorpyrifosmethyl [-0-3,5,6-trichloro-2-pyridyl 0,0-dimethyl phosphorothioate]

Parathion [0,0-diethyl 0-4-nitrophenyl phosphorothioate]

Sulprofos [0-ethyl 0-4-methylthiophenyl S-propyl phosphorodithioate]

Phosalone [S-6-chloro-2,3-dihydro-2-oxobenzoxazol3-ylmethyl-0,0-diethyl phosphorodithioate]

Acephate [0-,S-dimethyl N-acetylphosphoramidothioate]

Pyridaphenthion [0,0-diethyl 0-(2,3-dihydro-3-oxo2-phenyl-6-pyridazinyl)-phosphorothioate]

Temephos [0,0,0',0'-tetramethyl 0,0'-thiodip-phenylene bis(phosphorothioate)]

Phoxim [0,0-diethyl 0-(α-cyanobenzilideneamino) thiophosphate]

(2) Pyrethroid insecticides

Allethrin [(RS)-3-allyl-2-methyl-4-oxocyclopent2-enyl (1RS)cis, trans-chrysanthemate]

Permethrin [3-phenoxybenzyl (1RS)cis,trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate]

Phenothrin [3-phenoxybenzyl (1RS)cis,transchrysanthemate]

Tetramethrin [cyclohex-1-ene-1,2dicarboximidomethyl (1RS)cis,trans-chrysanthemate]

Furamethrin [5-(2-propynyl)-2-furylmethyl (1RS)cis,trans-chrysanthemate]

Resmethrin [5-benzyl-3-furylmethyl (1RS)cis, trans-chrysanthemate]

Fenvalerate [α-cyano-3-phenoxybenzyl α-isopropyl4-chlorophenylacetate]

Cyfluthrin [cyano-(4-fluoro-3-phenoxyphenyl)methyl 3(2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarboxylate]

Deltamethrin [(S)-2-cyano-3-phenoxybenzyl (1R,3R)-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropanecarboxylate]

Cypermethrin [(RS)-α-cyano-3-phenoxybenzyl (1RS,3RS;1RS;3SR)-3-(2,2-dichlorovinyl)-2,2dimethylcyclopropanecarboxylate]

Flucythrinate [(RS)-α-cyano-3-phenoxybenzyl (S)2-(4-difluoromethoxyphenyl)-3-methylbutylate]

Cyphenothrin [α-cyano-3-phenoxybenzyl d-cis, trans-chrysanthemate]

(3) Carbamate insecticides

Propoxur [2-isopropoxyphenyl methylcarbamate]

Carbaryl [1-naphthyl methylcarbamate]

BPMC [0-sec-butylphenyl methylcarbamate]

Carbofuran [2,3-dihydro-2,2-dimethylbenzofuran7-yl methylcarbamate]

Methomyl [S-methyl N-(methylcarbamoyloxy) thioacetimidate]

(4) Others

Propargite [2-(4-tert-butylphenoxy)cyclohexyl prop-2-ynyl sulfite]

Chlordane [1,2,4,5,6,7,8,8-octachloro2,3,3a,4,7,7a-hexanhyro-4,7-methanoindene]

Nonionic surfactants

Examples thereof are

(1) ethers of alkyl C₈ -C₁₂ and polyoxyethylene (2-8 moles) of the formula ##STR2## wherein alkyl is C₈ -C₁₂ and n is 2-8, such as polyoxyethylene nonylphenyl ether and the like

(2) ethers of alkyl or alkenyl alcohol C₁₂ -C₁₈ and polyoxyethylene (2-8 moles) of the formula

    alkyl(alkenyl)--O--(CH.sub.2 CH.sub.2 O).sub.n --H

wherein alkyl(alkenyl) is C₁₂ -C₁₈ and n is 2-8, such as polyoxyethylene lauryl ether and the like

(3) esters of fatty acid of C₁₂ -C₁₈ and polyoxyethylene (2-8 moles), such as polyoxyethylene oleate and the like

(4) polyoxyethylene alkylamines of alkyl or alkenyl amine of C₁₂ -C₁₈ and polyoxyethylene (2-6 moles), such as polyoxyethylene laurylamine and the like

(5) condensation polymer of formaldehyde (5-20 moles) and ether comprising naphthol (5-20 moles) and polyoxyethylene (4-40 moles)

(6) esters of glycerol and fatty acid (C₁₂ -C₁₈), such as glycerol oleate, glycerol stearate and the like

(7) esters of pentaerythritol and fatty acid (C₁₂ -C₁₈) such as pentaerythritol stearate and the like

(8) esters of sorbitan and fatty acids(s) (C₁₂ -C₁₈) and polyoxyethylene (4-20 moles) sorbitan and fatty acid(s) (C₁₂ -C₁₈), such as sorbitan monooleate, sorbitan stearate, sorbitan palmitate, sorbitan laurate, polyoxyethylene-sorbitan oleate and the like.

These surfactants may be used each alone or in the form of a mixture of two or more.

Thickeners

They are, for example, polyvinyl alcohol, xanthan gum, CMC, carrageenan, tragacanth gum, magnesium aluminum silicate like veegum (product of R.f. Vanderbilt Co., Inc.), Laponite (product of Laporte industries Ltd.) and gum arabic. The preferable are xanthan gum, polyvinyl alcohol, CMC, carrageenan, tragacanth gum, magnesium aluminum silicate and Laponite.

The agricultural chemical preparation of the present invention may additionally contain stabilizers such as pH regulators for the purpose of further improving the stability of active ingredients, preservatives for preventing the contamination due to microorganisms and/or agents for the depression of freezing point in order to prevent the preparation from freezing at cold area.

The stabilizers usable in the present invention include, for example, phosphates, aliphatic acid diethanolamide, butylhydroxytoluene and the like.

The preservatives usable in the present invention include, for example, PCMX, dehydroacetic acid, butyl p-hydroxybenzoate and the like.

The preparation of aqueous emulsion or suspension thus obtained in accordance with the present invention is characterized by the following advantages, as compared with a conventional emulsion or suspension preparation.

(1) Even active ingredients said to be chemically unstable are able to be stabilized as demonstrated in Tables 6, 7 and 13.

(2) Active ingredients which are liquid at room temperature are able to be formulated into the present aqueous preparation, and a mixture of a liquid active ingredient and a solid one is able to be formulated into the present aqueous preparation as shown in Examples 29 and 30.

(3) Nasal and eye irritations which have been unavoidable due to surfactants, having an HLB value higher than 11 are able to be markedly decreased as demonstrated in Table 16.

(4) Because of using a nonionic surfactant having an HLB value of 11 or less, the present preparation is superior in the spreadability onto the surfaces to be applied and residual effect against German cockroaches as shown in Table 15, and comparable in quick knockdown activity against house files, as compared with a commercially available emulsifiable concentrate.

(5) Stable spray solution is able to be easily prepared, when the preparation of the present invention is diluted into water.

The present invention will be illustrated in more detail with references to the following Examples which are only illustrative and not intended to limit the scope of the present invention. In Examples, the active ingredients used are expressed by each common name.

EXAMPLE 1

Fenitrothion (oily compound) (10 g) was mixed with sorbitan monooleate (HLB 4.3, 5 g), and the mixture was suspended in an aqueous solution of xanthan gum (0.6 g) in deionized water (84.4 g) at 25° C. to obtain an aqueous suspension preparation (100 g) of fenitrothion.

EXAMPLE 2

Example 1 was repeated, provided that fenthion (oily compound) was used in place of fenitrothion, thereby obtaining an aqueous suspension preparation of fenthion.

EXAMPLE 3

Example 1 was repeated, provided that cyanophos (oily compound) was used in place of fenitrothion, thereby obtaining an aqueous suspension preparation of cyanophos.

COMPARATIVE EXAMPLE 1

A mixture of fenitrothion (10 g) and polyoxyalkylene polystyrylphenyl ether (HLB 13, 15 g) was mixed with aqueous solution of diethyleneglycol monobutyl ether (15 g) in deionized water (60 g) to obtain an aqueous suspension preparation (100 g).

COMPARATIVE EXAMPLE 2

Comparative Example 1 was repeated, provided that fenthion was used in place of fenitrothion, thereby obtaining an aqueous suspension preparation of fenthion.

COMPARATIVE EXAMPLE 3

Comparative Example 1 was repeated, provided that cyanophos was used in place of fenitrothion, thereby obtaining an aqueous suspension preparation of cyanophos.

The compositions were stored in constant temperature baths for various periods of time, then emulsion condition of the composition and decomposition percentage of the active ingredient in the composition after the storage were checked and measured. The data are shown in table 1.

The decomposition percentage:

Concentration of active ingredients in the composition was analyzed by gaschromatograph, then the decomposition percentage was calculated by the following formula. ##EQU1##

                  TABLE 1                                                          ______________________________________                                                     Decomposition percentage of active                                             ingredient after storage at 40° C.                                      for 30 days (%)                                                    ______________________________________                                         Example No. 1     0.5                                                                      2     0.2                                                                      3     0.4                                                          Comparative 1     38                                                           Example No. 2     12                                                                       3     35                                                           ______________________________________                                    

Table 1 shows that preparations of Example No. 1-3 where a surfactant having HLB value of 4.3 was used are excellent in stability of active ingredients compared with Comparative Example Nos. 1-3 where a surfactant having HLB values of 13 was used.

EXAMPLES 4 TO 7 AND COMPARATIVE EXAMPLES 4 TO 6

In a manner similar to that of Example 1, each preparation having the composition as shown in the following table 2 was obtained.

                  TABLE 2                                                          ______________________________________                                                                Comparative                                                      Example No.   Example No.                                             Composition                                                                               4      5      6    7    4    5    6                                 ______________________________________                                         Fenitrothion                                                                              10     10     10   10   10   10   10                                (oily compound)                                                                polyoxyethylen                                                                            5      --     --   --   --   --   --                                nonylphenyl                                                                    ether (HLB 5.5)                                                                polyoxyethylen                                                                            --     5      --   --   --   --   --                                nonylphenyl                                                                    ether (HLB 7.5)                                                                polyoxyethylen                                                                            --     --     5    --   --   --   --                                nonylphenyl                                                                    ether (HLB 8.9)                                                                polyoxyethylen                                                                            --     --     --   5    --   --   --                                nonylphenyl                                                                    ether (HLB 10.9)                                                               polyoxyethylen                                                                            --     --     --   --   5    --   --                                nonylphenyl                                                                    ether (HLB 13.3)                                                               polyoxyethylen                                                                            --     --     --   --   --   5    --                                nonylphenyl                                                                    ether (HLB 15.0)                                                               polyoxyethylen                                                                            --     --     --   --   --   --   5                                 nonylphenyl                                                                    ether (HLB 16.0)                                                               Sodium     0.2    0.2    0.2  0.2  0.2  0.2  0.2                               dehydroacetate                                                                 Xanthan gum                                                                               0.6    0.6    0.6  0.6  0.6  0.6  0.6                               Deionized water                                                                           84.2   84.2   84.2 84.2 84.2 84.2 84.2                              ______________________________________                                    

EXAMPLE 8 TO 11 AND COMPARATIVE EXAMPLE 7 TO 9

Similarly, each preparation having the composition as shown in the following table 3 was obtained.

                  TABLE 3                                                          ______________________________________                                                                Comparative                                                      Example No.   Example No.                                             Composition                                                                               8      9      10   11   7    8    9                                 ______________________________________                                         Fenthion   5      5      5    5    5    5    5                                 (Oily compound)                                                                Polyoxyethylene                                                                           5      --     --   --   --   --   --                                lauryl ether                                                                   (HLB 5.5)                                                                      Polyoxyethylene                                                                           --     5      --   --   --   --   --                                lauryl ether                                                                   (HLB 7.1)                                                                      Polyoxyethylene                                                                           --     --     5    --   --   --   --                                lauryl ether                                                                   (HLB 8.6)                                                                      Polyoxyethylene                                                                           --     --     --   5    --   --   --                                lauryl ether                                                                   (HLB 10.4)                                                                     Polyoxyethylene                                                                           --     --     --   --   5    --   --                                lauryl ether                                                                   (HLB 14.1)                                                                     Polyoxyethylene                                                                           --     --     --   --   --   5    --                                lauryl ether                                                                   (HLB 15.6)                                                                     Polyoxyethylene                                                                           5      --     --   --   --   --   5                                 lauryl ether                                                                   (HLB 18.4)                                                                     Sodium     0.2    0.2    0.2  0.2  0.2  0.2  0.2                               dehydroacetate                                                                 Xanthan gum                                                                               0.6    0.6    0.6  0.6  0.6  0.6  0.6                               deionized water                                                                           89.2   89.2   89.2 89.2 89.2 89.2 89.2                              ______________________________________                                    

EXAMPLE 12 AND 13 AND COMPARATIVE EXAMPLE 10 TO 12

Similarly, each preparation having the composition as shown in the following table 4 was obtained.

                  TABLE 4                                                          ______________________________________                                                              Comparative                                                          Example No.                                                                              Example No.                                               Composition  12      13      10    11    12                                    ______________________________________                                         Diazinon     5       5       5     5     5                                     (oily compound)                                                                Polyoxyethylen                                                                              5       --      --    --    --                                    oleate (HLB 2.5)                                                               Polyoxyethylen                                                                              --      5       --    --    --                                    oleate (HLB 9.3)                                                               Polyoxyethylen                                                                              --      --      5     --    --                                    oleate (HLB 11.4)                                                              Polyoxyethylen                                                                              --      --      --    5     --                                    oleate (HLB 15.3)                                                              Polyoxyethylen                                                                              --      --      --    --    5                                     oleate (HLB 16.1)                                                              Potassium phosphate                                                                         0.1     0.1     0.1   0.1   0.1                                   Disodium     1.5     1.5     1.5   1.5   1.5                                   hydrogenphosphate                                                              Xanthan gum  0.6     0.6     0.6   0.6   0.6                                   deionized water                                                                             87.8    87.8    87.8  87.8  87.8                                  ______________________________________                                    

EXAMPLE 14 AND 16 AND COMPARATIVE EXAMPLE 13 TO 14

Similarly, each preparation having the composition as shown in the following table 5 was obtained.

                  TABLE 5                                                          ______________________________________                                                                  Comparative                                                       Example No.  Example No.                                           Composition   14     15      16    13    14                                    ______________________________________                                         Fenthion      5      5       5     5     5                                     (oily compound)                                                                Tetramethrin  0.5    0.5     0.5   0.5   0.5                                   (solid compound)                                                               Permethrin    2      2       2     2     2                                     (oily compound)                                                                Polyoxyethylene                                                                              5      --      --    --    --                                    laurylamine (HLB 6.5)                                                          Polyoxyethylene                                                                              --     5       --    --    --                                    laurylamine (HLB 7.8)                                                          Polyoxyethylene                                                                              --     --      5     --    --                                    laurylamine (HLB 10.9)                                                         Polyoxyethylene                                                                              --     --      --    5     --                                    laurylamine (HLB 14.1)                                                         Polyoxyethylene                                                                              --     --      --    --    5                                     laurylamine (HLB 16.5)                                                         Sodium        0.2    0.2     0.2   0.2   0.2                                   dehydroacetate                                                                 Xanthan gum   0.6    0.6     0.6   0.6   0.6                                   deionized water                                                                              86.7   86.7    86.7  86.7  86.7                                  ______________________________________                                    

Stability was listed in table 6.

                                      TABLE 6                                      __________________________________________________________________________                        Decomposition percentage                                             **        of active ingredient                                                 ** *   ** after storage at 50° C. for                                   HLB                                                                               S.C.                                                                               P.S.                                                                              1 month (%)                                                 __________________________________________________________________________     Example No.                                                                           4 5.5                                                                               2   OK 6                                                                  5 7.5                                                                               2   OK 8                                                                  6 8.9                                                                               2   OK 9                                                                  7 10.9                                                                              2   OK 12                                                          Comparative                                                                           4 13.3                                                                              2   OK 28                                                          Example No.                                                                           5 15.0                                                                              2   OK 43                                                                 6 16.0                                                                              2   OK 58                                                          Example No.                                                                           8 5.5                                                                               2   OK 2                                                                  9 7.1                                                                               2   OK 2                                                                  10                                                                               8.6                                                                               2   OK 2                                                                  11                                                                               10.4                                                                              2   OK 3                                                           Comparative                                                                           7 14.1                                                                              2   OK 8                                                           Example No.                                                                           8 15.6                                                                              2   OK 11                                                                 9 18.4                                                                              2   OK 26                                                          Example No.                                                                           12                                                                               2.5                                                                               2   OK 5                                                                  13                                                                               9.3                                                                               2   OK 6                                                           Comparative                                                                           10                                                                               11.4                                                                              2   OK 10                                                          Example No.                                                                           11                                                                               15.3                                                                              2   OK 15                                                                 12                                                                               16.1                                                                              2   OK 21                                                                                   Tetra-                                                                   Fenthion                                                                             methrin                                                                             Permethrin                                       Example No.                                                                           14                                                                               6.5                                                                               2   OK 2     1    0.1                                                     15                                                                               7.8                                                                               2   OK 2     1    0.1                                                     16                                                                               10.9                                                                              2   OK 4     5    0.3                                              Comparative                                                                           13                                                                               14.1                                                                              2   OK 11    8    0.6                                              Example No.                                                                           14                                                                               16.5                                                                              2   OK 14    16   0.8                                              __________________________________________________________________________      *Storage conditions: 1: 40° C., 30 days; 2: 50° C. one mont      3: 50° C., one week                                                     **Stability of emulsion                                                        OK . . . complete emulsion                                                     sep . . . seperated                                                            **                                                                             **HLB value of surfactants                                               

Table 6 shows that surfactants having HLB of 11 or smaller serve to control decomposition of insecticides at the small level and to have active ingredients performed as insecticides.

EXAMPLES 17 TO 30 AND COMPARATIVE EXAMPLES 15 AND 16

Similarly, each preparation having the composition as shown in the following table 7 was obtained. Stability was also mentioned in the table.

                  TABLE 7                                                          ______________________________________                                         Example                Amount   *    **   ***                                  No.    Composition     (g)      S.C. P.S. C.S.                                 ______________________________________                                         17     Fenitrothion    10                 1.0                                         Sorbitan monolaurate                                                                           5        3    OK                                               (HLB 8.1)                                                                      Xanthan gum     0.6                                                            deionized water 84.4                                                    18     Fenthion        10                 1.0                                         Sorbitan monooleate                                                                            5        2    OK                                               (HLB 4.3)                                                                      Xanthan gum     0.6                                                            Sodium dehydroacetate                                                                          0.2                                                            deionized water 84.2                                                    19     Propargite      30                 0.2                                         Sorbitan monooleate                                                                            5                                                              (HLB 4.3)                                                                      Polyvinyl alcohol.sup.a)                                                                       7        3    OK                                               Potassium phosphate                                                                            0.1                                                            Disodium hydrogenphos-                                                                         1.5                                                            phate                                                                          Sodium dehydroacetate                                                                          0.2                                                            Deionized water 56.2                                                    20     Propargite      40                 0.2                                         Sorbitan monooleate                                                                            5                                                              (HLB 4.3)                                                                      Polyvinyl alcohol.sup.a)                                                                       5        3    OK                                               Potassium phosphate                                                                            0.1                                                            Disodium hydrogenphos-                                                                         1.5                                                            phate                                                                          Sodium dehydroacetate                                                                          0.2                                                            deionized water 48.2                                                    21     Chlordan        60                 0                                           Sorbitan monooleate                                                                            5        2    OK                                               (HLB 4.3)                                                                      Polyvinyl alcohol.sup.a)                                                                       3.5                                                            deionized water 31.5                                                    22     Cyanophos       10                 0.5                                         Polyoxyethylene nonyl-                                                                         5        3    OK                                               phenyl ether (HLB 5.5)                                                         Xanthan gum     0.6                                                            deionized water 84.4                                                    23     Diazinon        30                 1.0                                         Polyoxyethylene oleate                                                                         5                                                              (HLB 9.3)                                                                      Polyvinyl alcohol.sup.a)                                                                       7        3    OK                                               Potassium phosphate                                                                            0.1                                                            Disodium hydrogenphos-                                                                         1.5                                                            phate                                                                          Sodium dehydroacetate                                                                          0.2                                                            deionized water 56.2                                                    24     Fenthion        40                 0.5                                         Polyoxyethylene lauryl                                                                         5        3    OK                                               ether (HLB 8.6)                                                                Polyvinyl alcohol.sup.a)                                                                       5                                                              deionized water 50                                                      25     Fenitrothion    10                 1.0                                         Permethrin      2                  0.1                                         Tetramethrin    1        3    OK   0.5                                         Sorbitan monooleate                                                                            5                                                              (HLB 4.3)                                                                      Xanthan gum     0.6                                                            Sodium dehydroacetate                                                                          0.2                                                            deionized water 81.2                                                    26     Fenitrothion    5                  2                                           Tetramethrin    0.5                5                                           Sorbitan monooleate                                                                            10       2    OK                                               (HLB 4.3)                                                                      Xanthan gum     0.6                                                            Sodium dehydroacetate                                                                          0.2                                                            deionized water 83.7                                                    27     Fenitrothion    10                 0.7                                         Tetramethrin    1                  0.7                                         Sorbitan monooleate                                                                            5        3    OK                                               (HLB 4.3)                                                                      Xanthan gum     0.6                                                            Sodium dehydroacetate                                                                          0.2                                                            deionized water 83.2                                                    28     Diazinon        40                                                             Sorbitan monolaurate                                                                           3                                                              (HLB 8.1)                                                                      Polyoxyethylene lauryl-                                                                        2                                                              amine                                                                          Polyvinyl alcohol.sup.a)                                                                       5        3    OK   0.7                                         Potassium phosphate                                                                            0.1                                                            Disodium hydrogenphos-                                                                         1.5                                                            phate                                                                          Sodium dehydroacetate                                                                          0.2                                                            deionized water 48.2                                                    29     Permethrin      15                 0.1                                         Thiabendazole   5                                                              Sorbitan monooleate                                                                            10       3    OK                                               (HLB 4.3)                                                                      Polyvinyl alcohol.sup.a)                                                                       3.3                                                            deionized water 66.7                                                    30     Fenitrothion    15                 0.9                                         AMICAL 48       5        3    OK                                               Sorbitan monooleate                                                                            10                                                             (HLB 4.3)                                                                      Polyvinyl alcohol.sup.a)                                                                       3.3                                                            deionized water 66.7                                                    Com-                                                                           para-                                                                          tive                                                                           Example                                                                        15     Tetramethrin    5                  12                                          Polyoxyethyelene nonyl-                                                                        5        1    OK                                               phenyl ether (HLB 16.0)                                                        Sodium dehydroacetate                                                                          0.2                                                            Xanthan gum     0.6                                                            deionized water 89.2                                                    16     Fenitrothion    10                 42                                          Tetramethrin    1                  14                                          Polyoxyethylene nonyl-                                                                         5        1    OK                                               phenyl ether (HLB 16.0)                                                        Sodium dehydroacetate                                                                          0.2                                                            Xanthan gum     0.6                                                            deionized water 83.2                                                    ______________________________________                                          *Storage conditions                                                            1: 40° C., 30 days; 2: 50° C., one month; 3: 50° C.,      one week                                                                       **Stability of emulsion                                                        OK . . . complete emulsion                                                     sep . . . separated                                                            ***Decomposition percentate of active ingredient (%)                           .sup.a) Polyvinyl alcohol having the polymerization degree of 1000 or les      and the saponification degree of 86.5 to 89.0 mole %.                    

EXAMPLE 31

Fenitrothion (10 g) was mixed with sorbitan monolaurate (10 g) (HLB 8.1), and the resulting mixture was mixed with a 0.6% by weight aqueous solution of xanthan gum (80 g) to obtain an aqueous emulsion preparation of fenitrothion (100 g) having an effective ingredient content of 10% by weight.

EXAMPLE 32

A mixture of phenothrin (50 g) and polyoxyethylenesorbitan trioleate (20 g) (HBL 11) was mixed with a 0.5% by weight aqueous solution of xanthan gum (30 g) to obtain an aqueous emulsion preparation of phenothrin (100 g) having an effective ingredient content of 50% by weight. After the composition was stored at 50° C. for one week, no physical change in emulsion was observed and decomposition percentage of phenothrin was 0.2.

EXAMPLE 33

A mixture of fenitrothion (5 g) and tetramethrin (0.5 g) was mixed with sorbitan monolaurate (HLB 8.1) (10 g) at about 60° C., and the resulting mixture was mixed with a 0.6% by weight aqueous solution of xanthan gum (84.5 g) to obtain a mixed aqueous emulsion preparation of fenitrothion and tetramethrin (100 g) having each effective ingredient content of 5% by weight and 0.5% by weight , respectively. After the composition was stored at 50° C. for one week, no physical change in emulsion was observed and decomposition percentages of fenitrothion and tetramethrin were 1.8 and 0.5, respectively.

EXAMPLE 34

A mixture of phenothrin (5 g), tetramethrin (0.5 g) and permethrin (1 g) was mixed with a mixture of sorbitan monolaurate (5 g) (HLB 8.1), sorbitan monopalmitate (HLB 6.9) (1 g) and polyoxyethylenesorbitan trioleate (HLB 11) (1 g), and the resulting mixture was mixed with 0.6% by weight aqueous solution of xanthan gum (86.5 g) to obtain a mixed aqueous emulsion preparation of phenothrin, tetramethrin and permethrin having each effective ingredient content of 5% by weight, 0.5% by weight and 1% by weight, respectively.

After the composition was stored at 50° C. for one week, no physical change in the emulsion was observed and decomposition percentages of phenothrin, tetramethrin and permethrin were 0.2, 0.8 and 0.1, respectively.

EXAMPLES 35 TO 38

                  TABLE 8                                                          ______________________________________                                                      (w/w %)                                                           Composition    35       36      37     38                                      ______________________________________                                         Active  Fenitrothion                                                                              10       --    --     --                                    ingredient                                                                             Fenthion   --       5     --     --                                            Daizinon   --       --    5      --                                            Cyanophos  --       --    --     5                                             Tetramethrin                                                                              --       --    0.5    --                                    Polyhydric                                                                             Sorbitan   5        --    5      5                                     alcohol monooleate                                                             type    (HLB 4.3)                                                              nonionic                                                                               Glycerol   --       5     --     --                                    surfactant                                                                             monostearate                                                                   (HLB 3.5)                                                              Thickener                                                                              Xanthan gum                                                                               0.6      --    0.6    0.6                                           Polyvinyl  --       5     --     --                                            alcohol                                                                Pre-    Sodium     0.2        0.2 0.5    0.2                                   servative                                                                              dehydro-                                                                       acetate                                                                Stabilizer                                                                             1/15M      --       --    Balance                                                                               --                                            Sorensen's                                                                     buffer                                                                         solution                                                                       (pH 7.73)                                                              Diluent Water      Balance  Bal-  --     Bal-                                          purified            ance         ance                                          according to                                                                   the Japanese                                                                   pharma-                                                                        copoeia                                                                Storage conditions                                                                            50° C. one week                                          P.S.**         OK       OK      OK     OK                                      C.S.***        0.5        0.5   Dai. 1.0                                                                              0.4                                                                     Tet. 1.0                                       ______________________________________                                          **Stability of emulsion                                                        OK . . . complete emulsion                                                     sep . . . separated                                                            ***Decomposition percentage of active ingredient                         

EXAMPLES 39 TO 40

                  TABLE 9                                                          ______________________________________                                         (w/w %)                                                                        Composition           39       40                                              ______________________________________                                         Active   Pyridaphenthion  10       --                                          ingredient                                                                              Prothiofos       --       10                                          Polyhydric                                                                              Sorbitan monopalmitate                                                                          5        --                                          alcohol type                                                                            (HLB 6.9)                                                             nonionic Sorbitan monolaurate                                                                            --       5                                           surfactant                                                                              (HBL 8.1)                                                             Thickener                                                                               Xanthan gum      0.6      0.4                                                  Guar gum         --       0.2                                         Preservative                                                                            Sodium dehydroacetate                                                                           0.2      --                                                   Lactic acid      --       0.4                                         Diluent  Water purified according                                                                        Balance  Balance                                              to the Japanese pharma-                                                        copoeia                                                               Storage condition     50° C., one week                                  P.S.**                OK       OK                                              C.S.***               0.5      2.0                                             ______________________________________                                          **Stability of emulsion                                                        OK . . . complete emulsion                                                     sep . . . separated                                                            ***Decomposition percentage of active ingredient                         

EXAMPLES 41 TO 46

                                      TABLE 10                                     __________________________________________________________________________     (w/w %)                                                                        Composition     41   42   43   44   45   46                                    __________________________________________________________________________     Active Temephos 10   --   --   --   --   --                                    ingredient                                                                            Resmethrin                                                                              --   --   3    --   --   --                                           Permethrin                                                                              --   20   --   4    --   --                                           Fenitrothion                                                                            --   --   --   5    --   10                                           Tetramethrin                                                                            --   --   --   1    5    1                                     Polyhydric                                                                            Sorbitan 5    --   --   5    --   --                                    alcohol type                                                                          monooleate                                                              nonionic                                                                              (HLB 4.3)                                                               surfactant                                                                            Polyoxy- --   --   --   --   5    5                                            ethylene-                                                                      nonylphenyl                                                                    ether                                                                          (HLB 5.5)                                                                      Polyoxy- --   50   10   --   --   --                                           ethylene-                                                                      sorbitan                                                                       trioleate                                                                      (HLB 11)                                                                Thickener                                                                             Xanthan gum                                                                             --   0.02 0.2  0.6  0.6  0.6                                          Polyvinyl                                                                               5    --   --   --   --   --                                           alcohol                                                                        Tragacanth gum                                                                          0.2  --   --   --   --   --                                    Preservative                                                                          Sodium de-                                                                              0.2  --   --   0.2  0.2  0.2                                          hydroacetate                                                                   Sorbic acid                                                                             --   0.1  --   --   --   --                                           Lactic acid                                                                             --   --   2    --   --   --                                    Diluent                                                                               Water purified                                                                          Balance                                                                             Balance                                                                             Balance                                                                             Balance                                                                             Balance                                                                             Balance                                      according to                                                                   the Japanese                                                                   pharmacopoeia                                                           Colorant                                                                              Blue No. 1                                                                              --   --   --   0.001                                                                               --   --                                    Storage conditions                                                                             50° C., one week                                                                            40° C., 30 days                     P.S.**          OK   OK   OK   OK   OK   OK                                    C.S.***         1.5  0.2  0.8  Per. 0.1                                                                            2    Fen. 5                                                               Fen. 1.2                                                                       Tet. 1.0  Tet. 3                                __________________________________________________________________________      **Stability of emulsion                                                        OK ... complete emulsion                                                       sep ... separated                                                              ***Decomposition percentage of active ingredient                         

EXAMPLES 47 TO 50

                  TABLE 11                                                         ______________________________________                                         Example               Amount   *     **   ***                                  No.    Composition    (g)      S.C.  P.S. C.S.                                 ______________________________________                                         47     Phoxim         12                  1.2                                         Sorbitan monooleate                                                                           5        3     OK                                               (HLB 4.3)                                                                      Polyvinyl alcohol.sup.a)                                                                      8                                                               deionized water                                                                               75                                                       48     Chlorpyrifos   5                   0.5                                         Polyoxyethylene                                                                               10       3     OK                                               nonylphenyl ether                                                              (HLB 10.9)                                                                     Polyvinyl alcohol.sup.a)                                                                      8                                                               deionized water                                                                               77                                                       49     Fenchlorofos   5                   2.0                                         Sorbitan monooleate                                                                           5        3     OK                                               (HLB 4.3)                                                                      Polyvinyl alcohol.sup.a)                                                                      9                                                               deionized water                                                                               81                                                       50     Malathion      10                  1.0                                         Sorbitan monooleate                                                                           5        3     OK                                               (HLB 4.3)                                                                      Xanthan gum      0.6                                                           deionized water                                                                                84.4                                                    ______________________________________                                          *Storage conditions                                                            1: 40° C., 30 days; 2: 50° C., one month; 3: 50° C.,      one week                                                                       **Stability of emulsion                                                        OK . . . complete emulsion                                                     sep . . . separated                                                            ***Decomposition percentage of active ingredient (%)                           .sup.a) Polymerization degree of 1000 or less, saponification degree of        86.5 to 89.0 mol %.                                                      

EXAMPLES 51 TO 55

                  TABLE 12                                                         ______________________________________                                         Example               Amount   *     **   ***                                  No.    Composition    (g)      S.C.  P.S. C.S.                                 ______________________________________                                         51     Allethrin      5                   0.2                                         Polyoxyethylene                                                                               5        3     OK                                               Sorbitan trioleate                                                             (HLB 11)                                                                       Polyvinyl alcohol.sup.a)                                                                      9                                                               deionized water                                                                               81                                                       52     Rethmethrin    5                   0.4                                         Sorbitan monooleate                                                                           5        3     OK                                               (HLB 8.1)                                                                      Polyvinyl alcohol.sup.a)                                                                      9                                                               deionized water                                                                               81                                                       53     Cyphenothrin   10                  0.1                                         Sorbitan monooleate                                                                           5        3     OK                                               (HLB 8.1)                                                                      Polyvinyl alcohol.sup.a)                                                                      8                                                               deionized water                                                                               77                                                       54     Flucythrinate  1                   0.1                                         Sorbitan monooleate                                                                           5        3     OK                                               (HLB 8.1)                                                                      Polyvinyl alcohol.sup.a)                                                                      9                                                               deionized water                                                                               85                                                       55     BPMC           2                   1.5                                         Polyoxyethylene                                                                               5        3     OK                                               nonylphenyl ether                                                              Polyvinyl alcohol.sup.a)                                                                      9                                                               deionized water                                                                               84                                                       ______________________________________                                          *Storage conditions                                                            1: 40° C., 30 days; 2: 50° C., one month; 3: 50° C.,      one week                                                                       **Stability of emulsion                                                        OK . . . complete emulsion                                                     sep . . . separated                                                            ***Decomposition percentage of active ingredient (%)                           .sup.a) Polymerization degree of 1000 or less, saponification degree of        86.5 to 89.0 mol %.                                                      

EXAMPLE 56

    ______________________________________                                         Composition           Amount (g)                                               ______________________________________                                         Fenthion              10                                                       Polyoxyethylene arylphenyl ether                                                                     5                                                        condensation polymer of                                                        formaldehyde (HLB 10)                                                          Polyvinyl alcohol*    8.5                                                      deionized water       76.5                                                     ______________________________________                                          Stability (50° C., 10 days)                                             Dispersion: No change                                                          Decomposition of Fenthion 1.5%                                                 *The same as that in Table 11.                                           

                  TABLE 13                                                         ______________________________________                                                       Preparation                                                                               Conventional                                                                   solubilized                                                         Aqueous emulsion                                                                          oil-in-water                                                        preparation of                                                                            preparation                                                         the present                                                                               (anionic                                                            invention  surfactant)                                           ______________________________________                                         Content of active                                                                              Fenitrothion Fenitrothion                                      ingredient      10% by weight                                                                               10% by weight                                     Decomposition                                                                             1 Month  0            37.5                                          percentage (%)                                                                            3 Months 0.4          53.9                                          (Stored at 40° C.)                                                                 6 Months 0.6          not calculable                                ______________________________________                                    

Table 13 shows that fenitrothion which is unstable in the conventional solubilized oil-in-water preparation is able to be stabilized, in accordance with the present invention.

Insecticidal activity test

The preparation of aqueous suspension obtained in Example 26 is compared in knocking activity and residual effects respectively with the conventional emulsifiable concentrate obtained in Comparative Example 17 whose composition is:

    ______________________________________                                         Fenitrothion              5                                                    Tetramethrin              0.5                                                  Calcium alkylbenzenesulfonate                                                                            2.3                                                  (anionic surfactant)                                                           Polyoxyalkylene(C.sub.2-3, n = 5-10)                                                                     2.2                                                  alkyl (C.sub.12-15)ether                                                       Polyoxyethylene(n = 5-10)octylphenyl ehter                                                               0.5                                                  Xylene                    20                                                   Kerosene                  69.5                                                 ______________________________________                                    

(1) Insecticidal effect against adult house flies by a filter paper contacting method

Adult flies were released onto a treated filter paper with each preparation immediately after treatment

    ______________________________________                                                dosage        50 ml/m.sup.2                                                    dilution      10 folds                                                  ______________________________________                                    

                                      TABLE 14                                     __________________________________________________________________________                          (%) at indicated minutes after treatment                                                                   Mortality                                          Knock down ratio (%)   KT.sub.50                                                                           (%)                                                3 5  7  10 15 25 35 60 (minute                                                                             After 24                      Preparations tested  (min.)                 second)                                                                             hours                         __________________________________________________________________________     Aqueous suspension of the present invention                                                         0 13.3                                                                              43.3                                                                              80.0                                                                              93.3                                                                              100                                                                               100                                                                               100                                                                               7' 37"                                                                              100                           (Example 26)                                                                   Conventional emulsifiable concentrate                                                               0 16.7                                                                              46.7                                                                              76.7                                                                              96.7                                                                              100                                                                               100                                                                               100                                                                               7' 14"                                                                              100                           (Comparative Example 17)                                                       __________________________________________________________________________

The preparation of aqueous suspension in accordance with the present invention shows quick knock down activity similar to that of the conventional emulsifiabler concentrate.

(2) Insecticidal effect against German cockroaches by a glass plate contacting method

Cockroaches are released onto a glass plate treated with solution of each preparation at indicated days and mortality was counted.

dilution : 10 folds

dosage : (50 ml/m²)

                  TABLE 15                                                         ______________________________________                                                              Continuous contacting at                                                       the same surfaces                                         10-fold diluent (50 ml/m.sup.2)                                                                     Mortality (%)                                             Preparations                                                                               Days after   After      After                                      tested      treatment    24 hours   48 hours                                   ______________________________________                                         Aqueous     Immediately after                                                                           100        --                                         emulsion    After 1 week 100        --                                         of the      After 2 weeks                                                                               100        --                                         present     After 3 weeks                                                                               100        --                                         invention   After 4 weeks                                                                               96.7       100                                        (Example 26)                                                                   Conventional                                                                               Immediately after                                                                           100        --                                         emulsifiable                                                                               After 1 week 100        --                                         concentrate After 2 weeks                                                                               86.7       100                                        (Comparative                                                                               After 3 weeks                                                                               73.3       100                                        Example 17) After 4 weeks                                                                               50.0       86.7                                       ______________________________________                                    

As is clear from the above results, the preparation of aqueous emulsion in accordance with the present invention is superior in the residual effect against German cockroaches to that of the conventional emulsifiable concentrate

Toxicity

                  TABLE 16                                                         ______________________________________                                                    Preparations                                                                         10% Aqueous   Commercially                                                     emulsion of   available 10%                                                    fenitrothion in                                                                              emulsifiable                                                     accordance with                                                                              concentrate of                                                   the present   fenitrothion                                                     invention     (Comparative                                    Test items       (Example 1)   Example 18*)                                    ______________________________________                                         1    Acute oral  LD.sub.50 (ml/kg)                                             toxicity test                                                                               ♂   ♀ ♂ ♀                                 Mice         >20.0     15.0      7.1    9.8                                    Rats           4.5      5.4      3.4    4.0                                    2    Acute dermal                                                                               LD.sub.50 (ml/kg)                                             toxicity test                                                                               ♂   ♀ ♂ ♀                                 Mice         >10.0    >10.0    >10.0  >10.0                                    Rats         >10.0    >10.0    >10.0  >10.0                                    3    Eye         Original liquid                                                                              Original liquid                                      irritation test                                                                            shows no      shows irritation                                     Rabbits     irritation    to a slight or                                                   (negative)    medium degree                                   4    Skin        Original liquid                                                                              Original liquid                                      irritation test                                                                            shows no      show irritation                                      Rabbits     irritation    to an extremely                                                  (negative)    slight degree                                   ______________________________________                                          *                                                                        

     Fenitrothion           10                                                     Calcium alkylbenzenesulfonate                                                                           2.3                                                   (anionic surfactant)                                                           Polyoxyalkylene(C.sub.2-3, n = 5-10)                                                                    2.2                                                   alkyl (C.sub.12-15)ether                                                       Polyoxyethylene(n = 5-10)octylphenyl ether                                                              0.5                                                   Xylene                  20                                                     Kerosene                65                                                

The preparation according to examples 35 shows the same toxicity as that of Example 1. 

We claim:
 1. A stable, water based insecticidal preparation in the form of an aqueous emulsion or suspension which comprises(1) 0.5-60% by weight of fenitrothion (2) 0.3-50% by weight of sorbitan monooleate (3) 0.02-7% by weight of xanthan gum (4) the balance of water. 